JPH0153549B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a video signal switching device.

Video signal switching devices are becoming larger in scale, and some devices have appeared whose switching matrices are composed of hundreds of inputs and outputs. However, at present, a switch including a unit integrated switching circuit has several tens of inputs, and a large-scale switching device is constructed by combining these. Conventionally, in this configuration, the switching devices are connected in multiple stages, and the switching device in the previous stage controls the switching of the cross points, and the switching device in the subsequent stage also controls the switching of the cross points. However, in this configuration, a control logic circuit for controlling the cross points in the switching circuit in each switch is also required for the subsequent stage, the number of control signal lines becomes enormous, and the video signal is transmitted through multiple switchers. This has the disadvantage that the characteristics of the video signal deteriorate because the signal passes through it.

Incidentally, the aforementioned switching device is supplied with a binary coded control signal as switching control information.
After passing through the hold circuit and decoder circuit, one signal is sent to each of the multiple cross points in the switching circuit.
A plurality of switching control signals in one-to-one correspondence are generated, and cross points are selected using these signals.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a video signal switching device that can configure a switching device without connecting multiple switching devices as in the prior art.

According to the present invention, a first switching circuit (element) having a plurality of cross points, a second switching circuit (element) that switches the output of the first switching circuit, and a binary coded switching circuit from the outside. A hold circuit that holds control information, a decoder circuit that receives a code that selects a plurality of cross points of a first switching circuit from among the outputs of the hold circuit and generates switching control signals corresponding to each of the plurality of cross points, and a hold circuit. a comparison circuit that receives a code indicating the selection of a switching device among the outputs of the circuit, compares this with a predetermined code corresponding to this switching device, and controls a second switching circuit based on the comparison output. A vessel is obtained.

Next, the present invention will be described in detail with reference to the drawings showing one embodiment of the present invention. FIG. 1 is a diagram showing an embodiment of the present invention, and in the switch shown in FIG.
The binary code switching information i is held in the hold circuit 1 at the timing of the trigger signal t.
A code with switching information of the first switching circuit 2 having multiple cross points among the held signals
_i1 enters the decoder circuit 3, where it is converted into switching control signals S corresponding to a plurality of cross points in the switching circuit 2, and sent to the switching circuit 2. On the other hand, the code _i2 indicating the selection of the switch among the held outputs enters the comparator circuit 4, where it is compared with the predetermined code corresponding to this switch generated by the code generation circuit 5 to find a match. The cross point of the second switching circuit 6 is closed by the signal output shown. By doing this, the function of the decoder circuit 3 can be made equal for all the switches, and when the switching device is composed of a plurality of switches, it is possible to receive the output of each switch and select one of the switches. There is an advantage that no other selector is required.

Fig. 2 is a block diagram of a case where a large-scale switching device with n inputs to 1 output is made by combining the switching devices 7, 8, ..., 9 according to the present invention, and in this case, the output of each switching device is connected by a line. This eliminates the need for means for selecting the output of each switch, and prevents deterioration of video signal characteristics. Furthermore, if a plurality (m) of the configurations shown in FIG. 2 are prepared, a large-scale switching device having a matrix of n inputs to m outputs can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a switching device made by combining switching devices according to the present invention. In the figure, 1...Hold circuit, 2...Switching circuit with multiple cross points, 3...Decoder, 4...Comparison circuit, 5...Code generation circuit, 6...
...Switching circuit, 7, 8, 9...Switching device.

Claims (1)

[Claims] 1. A first switching element having a plurality of cross points, a second switching element that switches the output from the first switching element, and a code and a switch that indicate the selection of a binary coded cross point from the outside. a hold circuit that holds switching control information including a code indicating selection of a cross point in the first switching element; a decoder that generates a corresponding switching control signal; and a decoder that receives a code indicating the selection of a switching device from among the outputs of the hold circuit, compares it with a code corresponding to a predetermined switching device, and controls the second switching element according to the comparison result. A video signal switching device comprising: a comparison circuit for controlling switching.